Communities

IET Communities provide like-minded people with opportunities to share ideas, collaborate, learn and network. With more than 100 Local and Technical Networks around the world, you can feel confident of finding a community that suits your interests.

I 'm self employed but I do some work for a company that produces equipment to optimise voltage. Basically they supply a transformer with secondary windings to give outputs of about 10,15,20% less than the input voltages. A survey of a site is done to establish if the local voltage is high enough to allow a worthwhile reduction. The transfomer is sized to suit the existing load + say 15%. In the past we have stuck to supplying lighting loads and concentrated on old style tubes and SONs. Savings of 30+% and 20+% are achievable in Kwh. Payback can be in the order of 9-12 months on 30Kva systems that are running 24/7. Hi Frequency tubes offer only minimal savings. The TX is fitted downstream of the Dist Board which we prefer to be dedicated to lighting. Our experience tells us some loads other than lighting e.g. ticket m/c in a car park are voltage sensitive and complicate the wiring installation that makes the system unattractive to the end user. I know that other organisations use the same principle accross the whole supply to a building and may settle for a 5-7% voltage reduction to achieve an 10-11% kwh saving. Instalation downstream of a lighting DB tends to be straightforward and only involves a mains cable. Putting a unit accross a main building supply clearly could be a major disruption

Only solution is to give the input supply to an electronic gadget which will continuousey monitor the input voltage and instantaneousy adjust the output to normal value. The trouble is that the electronic eqipment must be capable of delivering the full load continueousely. IT WILL BE VERY COSTLY. In electromagnetic era, such eqipments are called SERVO CONTROLLED VOLTAGE STABILISER. In both cases they are FEED BACK CONTROL SYSTEMS and all mathematical laws of control systems design are applicable to them.

Definetely. But efficiency namely Lumens output per watt will be maximum at the designed voltage only.

There are two types of loads. One is Constant Impedence(CI). Other is Constant Horse Power (CHP). Normal incandecent lamps, heaters etc are CI. I am not in a position to say which type present type of compact flurocent lamps. But definety their charecteristics are predominently CI.Many Industrial motors are CHP meaning the load is decided by the consumer and no variation due to voltage.

In case of CI, the load will be proportional to the square of the voltage. Hence voltage reduction means reduction in power output. But in case of CHP, the power output will be same but the motor will draw more current and will have more heat loss and less efficiency.But for practical purposes we can assume no change in power output.

If there is a reduction in voltage and if the loads are predominantly industrial, then reduction in voltage will not cause appreciable reduction of power output.

But if the load is predominantly CI, then there will be appreciable reduction of power output. In Kerala during evening peak the load is predominantly CI. The taps of substation transformers are meant to give sufficient voltage for the consumer.But if there is a power shortage during evening peak,NOT ENERGY SHORTAGE FOR THE DAY,then it is customary in Kerala to reduce substation transformer taps to reduce power consumption.!!!!!

Just to answer the point about reduced light. In practice you can normally reduce the volts without any appreciable difference to the eye. Think about these low consumption bulbs which to my mind give out noticably less light. The savings depend on the lamp. Old style tubes can render energy savings of over 30%. The new Hi Frequency ballast tubes dont render much saving, perhaps 5%. They also vary significantly as we have this style of lamp under test at around 160 volts! and they seem to last Ok. Remember in all of this that the devices are designed to work at voltages down to 230? minus 10% i.e. 207 volts...depending on who you ask! In my view if we are going to meet the energy savings targets that the Government is talking about we will all need to get used to a lot less ambient light

I disagree with immediate above statement. In case of bulbs which gives light by heating a tungston filament, the reduction in light output will be much more than the reduction in voltage. But in case of flurocent lamps, the reduction in light will not be so high as in case of tungston filament lamps. If any one is satisfied with the light output at reduced voltage, an economical way is to use a lower wattage lamp. But unfortunately required correct wattage lamp is not available. If any body wishes to use voltage control for correct light output, it is suggested to use fluorescent lamps. Usually fluorescent lamps consume only less than 25% of power for same light output.

My only objection is that you are using the word OPTIMISATION instead of the word CONTROL.Control is the action on input while optimisation is our aim to have desired output. If you are a supplier of electricity, voltage optimisation has some meaning.

I accept what you are saying. I believe that I was responding to the original enquirer's use of the word. This is a term that has become more widly used in this context since it has been adopted by one of our much larger international competitors in the last couple of years. As a matter of interest we don't use that word in any of our literature.
Regards

I wish to add that in our younger days ENERGY CONSERVATION was not at all a criterion because of relatively cheap oil. Then our CONVENIENCE was more important. That was why there was a practice of illumination control by voltage reduction as mentioned by you was videly used then.Now every unit of energy must be saved. Again then or now interest on capital invested for energy saving must be less than the cost of energy saved.

If we could put this subject into an Industrial context,with load 1500KVA in one area. Large manufacturing plant with lots of VSD loads, servo drives and high frequency lighting in various areas. Now certain new Voltage Optimsation companies are indicating 8% savings (13% actual cost reduction)across the board once installed at the L.V. source. Hence, there is a wide variance of load types plus energy controlling devices in place (VSD etc).

Do you or other forum members have experience or a firm opinion good or bad?

Do you prefer voltage optimisation at the source or locally at lighting boards?

The voltage optimisation companies are correct in most of the cases. Suppose we have a 100W incandecent bulb giving X Lumens output. If the voltage is varied to a lower value such that the electrical output is 90% of normal power. Then the lumen out put will be definetely less than 90% of normal output.

In general all electrical equipments will work best if the voltage etc are as per specification of the manufacturer.

Hi
I can point you towards an informative and educational pdf at Link removed_Optimisation.pdf regarding this subject which should answer your questions if you need further information please contact me and I would be happy to assist.

Voltage Optimisation & Regulation has developed a lot since this thread was started back in 2007, and has received the approval of the CARBON TRUST as a way companies can reduce their electricity usage and carbon footprint. They have developed a great document on the subject which is worth reading - have a look at Link removed/cut-carbon-reduce-costs/products-services/technology-advice/Pages/voltage-management.aspx

e-fficient energy systems manufacture the most technologically advanced VO+R systems in the UK and if you are considering whether VO may be of use to you we'd be more than happy to help....

Please have a look at our website at e-fficientenergy.co.uk for more details